Zinc Oxide from Zamak Injection Waste

The generation of zinc oxide (ZnO) from the valorisation of waste generated within the industrial processes of injection of zamak, according to estimations carried out for the project LIFE+ GREENZO could reduce up to 425 000 tons/year the waste generated in Europe for this process, with the consequent implication on waste management associated costs.

The zamak is being used for the manufacturing of injection-moulded pieces in multiple products and industrial sectors. It is an alloy mainly composed of zinc (Zn), aluminium (Al), magnesium (Mg) and copper (Cu), which is provided in form of ingots.

The pieces injected always have rugosities and imperfections that must be corrected using polishing treatments with pieces covered of abrasive products (chips, knurls or stones) and water. Later, the already polished zamak pieces can go through finishing processes of electrodeposition or painting.

The process generates a great variety of waste, e.g. slag from smelting (collected from the smelting deposit, oxidised as the material on the surface is in contact with the atmosphere), the sludge from vibration (resulting from the polishing process) and others as chips of defective parts with or without surface bath, etc.

Currently, some of this waste is managed as non-dangerous waste for its material valorisation in 2nd quality ingots, in the case of slag from smelting, chips or defective parts. Nevertheless, the sludge from vibration is managed as a dangerous waste for its further deposit in safety deposits.

According to the International Zinc Association, the worldwide consumption of ZnO is estimated in more than 1.2 million tons per year. From this, 75% is obtained from primary sources (mining) and only 25% of it is obtained from secondary methods (recycling).

Recycling is annually increasing according to the progress of production technologies and zinc recycling. Nevertheless, notwithstanding the multiple research actions for the revalorisation of metallic waste, there is not in the market any industrial process that allows the obtention of 1st quality ZnO from non-ferrous metallic waste. That is why the Life+GREENZO project has the aim to develop a compact pilot plant for the recuperation of this waste in form of ZnO. This plant will use the plasma arch technology.

Hazael Seguí, technical responsible of Worteurop, says “zinc oxide is the most used compound of zinc and it is used in the vulcanisation of rubber, as well as in the ceramic industry, although it has multiple application niches”, and adds: “there is ZnO of different purity that makes it appropriate, for example, for the pharmaceutical industry”, and “there are special grades of zinc oxide that can be used in specific applications that require concrete functionalities”.

The most important applications are: rubber, ceramics and concrete, plastic and linoleum, pigments and coatings, cosmetics, medical and dental products, catalysers, desulfurisation, varistors fertilisers, animals feed and dietary supplements, as well as synthesis of chemical products. Nevertheless, there is a serie of emerging applications in the electronics and optoelectronics areas thanks to the specific optic and electric characteristics of this semi-conductor. Among others, it is applied in light emitting diodes (LEDs), solar cells, sensors and actuators, in spintronics, in liquid crystal display (LCD) screens, or in textiles.

This project will be developed in 3 years, and it is funded by the European Commission through the financing instrument LIFE13 ENV/ES/000173 GREENZO. It is coordinated by AIJU and the research centre ITQ-CSIC as well as the companies WORTEUROPE and CAUCHOS KAREY participate in this project. The project website was posted in September 2014 and its English version towards the end of October. You can visit it at www.lifegreenzo.eu.

About AIJU:

AIJU is a non-profit making technological center funded in 1985 with the aim to boost the children’s products and leisure industries, and their connected and related industries through technological innovation transfer. With this aim, it has a multi-disciplinary staff of 75 professionals that develop their tasks in the diverse areas of which AIJU is composed and has the necessary infrastructure to manage the diverse tasks for which they are well-known.

In this project participates the Innovation and Sustainability department, specifically the Environmental and Energy areas, both with contrasted capacity and experience to ensure the consecution of the objectives of the project.

The main working lines of the Environmental area are the implementation of clean technologies (assessment of the feasibility of the pilot plant for the valorisation of waste, the development of environmental technological solutions, etc.); the sector adaptation to the emerging environmental legislation (adaptation of the children’s products sector to the new European Directives on waste, minimisation, energetic valorisation and the des-cataloging of dangerous waste, etc.) and the LCA and products eco-design.

On the other side, the Energy area has as objectives the R+D+I of new devices for the generation and storing of energy, the development of new fully-controlled and automated processes for the obtention of “clean fuels”, or the development of supports or last generation catalysers that increase the energetic efficiency of the processes, among others.

For further information, visit: www.aiju.info.

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